Process for utilizing sapped tanning liquors.



To all 21:71am it may concern: 3 Be it known that I, GEORGE W UN T-E Boner. w. CHILDS, or xsw YORK, X. Y.

a g PRocEss FOR UTILIZING SAPPED TANNING LI 'UoRs.

CnnLns, of

h ew iork city, in the county and State of New iork, have invented a certain new and useful Improvement in Processes for Utiliz-' lowing is a specification.

This application is a division of my application Serial 2317.141, filed May 16', 1906, which is limited to a process for utilizing sap )ed tanning liquors containing mineral acig impurities. The process herein claiincd is applicable to waste tanning liquors containing alkaline impurities, as lime or linie ing Sapped 'lanni a; Liquors, \\'hereof the. folcompounds, to produce therefrom a leather dressing of the character described and claimed in Letters Patent of the United States #875,653, granted to me December 3], 1907.

It is the object of myinvention to )roduce a liquid dressing particularly applica do to the manufacture of leather, such as sole. leather, which itis desired shall have the greatest degree of solidity possible with the necessary degreeofflexihility. Allprocessesformaking such leather have heretofore involved two stages;l"irst, the hides are subjected to the action of a liquor comprising active tannic ma.- terial until combined with all of the tannin with which they are capable of combining, and second, the leather thus tanned is then subjected to a loading process, which usually consists in impregnating the leather with concentrated bark ext ract.

My improved process, is advantageous in that sapped or exhausted organic tanning liquors which are usually wasted, are thereby utilized to form an inert leather dressing which is an efficient substitute forthe more costly active tannic material heretofore e m plo 'ed for loading purposes. In order to ma 'e such leather dressing it is necessary to eliminate such impurities as have accrued in said liquors, from the addition of chemicals thereto or the formation of chemical compounds therein. For instance, if the waste lquor is from an acid tanning yard and con- 'tams sulfuric or other non-volatile mineral acid, it may be neutralized by the addition of alkali, or the acid; may be precipitated as salts by the addition of suitable reagents, as described in my application Serial #317,141. 011 the other hand, if the waste liquor is from a non-acid yard and contains lime or lime compounds, in accordance with the process y Specification of Letters Pate ht-- Orig'inal application filed May GilJQOG, Serial No. 317,141. Divided and this Serial No. 411,720.

and concentrated may hausted organic tan liquors Patented Sept. 15, 1908.

application filed. January 20, 1908.

herein claimedsuch impurities may be recipitated by the addition of chemicals forming insoluble mmnpounds with-lime. For instance, ammonium oxalate, sodium hosphate, sodium fluorid' or carbon tliOXl( gas may be employed to effect such precipitation. Said 5 )erit liquor may then be heated until the volatile impurities, for instance, acetic, propioni or but-yrie acids are eliminated, and the resultant liquid is concentrated conveniently by continued heating in cacao, until it attains a specific gravity of from 1.05 to 11.3, and becomes a leather dressing adapted for the purposes specified.

'lhe otherwise waste liquors thus purified be utilized as a dressing to increase the solidity of leather, as follo\vs:-llides which have been subjected to the. action of a tanning solution until'they have combined-with\ zqiproximatcly all the tannin with which they will combine, are then impregnated with said leather dressing in any convenient manner for instance, such a leather may he placed in a rotary drum and said concentrate. preferably heated, introduccd to said drum, convenientlythrough a hollow axle or trunnion thereof, and the revolution of said drum continued until said concentrate is absorbed by the leather and fills the pores of the la-ttcr so that, when dried, the residue of the dressing in the leather not only renders the latter more solid than if it had not been impregnated with said dressing, but also adds materiall to its final weight. It may be observed that if said dressing were of less specific gravity, there would not be sutlicient solid residue thereof when the leather'is dried to effect the result desired. Moreover, if said dressim were of a greater specific gravity, it word not be absorbed by the leather:

I do not desire to limit myself to all the 1 details of procedure above enumerated, as various modifications may be made therein without departing from the essential features of my invention, as defined in the appended claims.

I claim v 1. The process of treating sapped or excontaining alkaline mineral impurities and adapting them for impregnating leather, which consists in] precipitating said impurities by the addition of a chemical capable of forming an insoluble compound therewith; separating the precipitate; then heating the supernatent liquor m racuo until the volatile impurities areeliminated and the resultant liquid is concentrated to a specific gravity of from 1.05 to 1.3.

2. The process of treating sapped or exhausted organic- 1:11 liquors containing alkaline mineral impurities and adapting them for impregnating leather, which consists in precipitatingsaid impurities by the addition of a chelinical capable of forming an insoluble compound therewith; separating the pre' cipita-te-and comrentra-ting the resultant liquid to a specific gravityof from 1.05 to 1.3. 3. The process of treating sapped or ex-' hausted organic tan liquors and adaptmg a e 9,6091 7 pl them for impregnating leather, which con slsts in precipitating lime compounds there'- in, by adding :1- chcmical capable of forming an insoluble compound with lune separating the precipitate and concentrating the -resultant liquid to a specific gravity of from 1.0.5

to 1.3. 1 i 1 In testimony whereof, I have hereunto signed my name at New York City, in the county and State of New l'ork, this seventeenth day of January 19 Q8. v

GEORGE W. CHILDS. .Witnesses: I

J .\'o. P. Axmnson, W; G. Honrom 

